Unanticipated and undesirable corneal curvature changes resulting from contact lens wear have been reported. In recent years some clinicians have tried purposely to induce these changes by special contact lens fitting techniques, in an attempt to reduce or alleviate myopia. This procedure, often referred to as orthokeratology, has sparked considerable controversy. It represents a departure from the traditional viewpoint that the goal of successful contact lens fitting is to avoid any corneal change. The fact exists, however, that this procedure is being practiced by a growing number of practitioners and has excited the interest of the public through the popular media. In spite of this interest the only source of information about the success of this technique comes from the paractitioners themselves and the data are generally limited and sometimes blatantly biased. Nevertheless, there are sufficient positive results documented that the technique can no longer be ignored as a potential clinical procedure. There is a need for a controlled evaluation of the methods used and the results produced. The proposed project is intended to provide carefully controlled clinical and laboratory studies to evaluate the visual and corneal changes resulting from using contact lenses to modify myopia. A group of myopic patients will be fitted by recommended orthokeratology procedures. Another group will be fitted by traditional fitting procedures and will serve as a control. Both will be evaluated by the following testing procedures: a. Keratometry and photo-keratoscopy; b. Pachometry; c. Psychophysical visual acuity testing; d. Refractive error measurements using automatic objective and traditional clinical methods; e. Biomicroscopy; f. Tear film break-up time.